kiimzi, this is the second person's thread you have moved in on. You really need to start your own thread.
Sarah, sometimes parts of their bodies will get exposed to more or less light and react differently. I remember once someone posted a picture of her chameleon who'd been sunning himself up close to the wire mesh and when he moved away the pattern of the mesh was visible on his skin. Maybe something like that happened. While it's something you want to keep an eye on, unless it recurs on a regular basis, I don't know that it sounds like it warrants a vet visit.